1) Pulled gas tank off and dumped out what gas was in it. 2) Added about a 1/4 tank of gas back in it. 3) Added a hand full of BB's and put the gas cap back on. 4) Shook the tank several times to agitate the BB's, they will act as a sand blaster and remove any garbage build up you might have on the walls of the tank, you may want to cover the gas cap with a rag as some may fuel may seep out . 5) Dumped out the fuel along with the BB's. 6) Add another 1/4 tank of gas without BB's and shake it up to rinse any remaining material out. 7) Pulled the fuel line off and blew out with air. 8) Removed the carb and tried to keep some fuel in the bowl so you can see if there is anything floating around. 9) Removed the main jet and blew it out along with blowing out any of the other passages in the carb. 10) Use a clean lint free cloth to wipe out the bowl and the intake side of the carb. Remove the electric choke and clean it and blow out the area it seats into. 11) Use a rag to wipe out the air filter tube that connects to the carb. 12) Reassemble the carb and install it back on the motor. 13) Replace fuel filter. 14) Hook everything back up and install the tank and fill with new fuel.
By doing this you have just covered the entire fuel system and have removed any contamination that could occur. It better to take your time and do it right the first time.